Miniature, durable polarization devices

ABSTRACT

Polarizing optical devices described herein, and polarizing optical devices resulting from methods described herein, can be small and can have high heat tolerance. Wires of wire grid polarizers can be attached directly to prisms of the polarizing optical devices, allowing for small size. Multiple polarizing optical devices can be attached by adhesive-free bonding techniques, allowing high heat tolerance.

CLAIM OF PRIORITY

This is a divisional of U.S. patent application Ser. No. 15/943,324,filed on Apr. 2, 2018, which claims priority to U.S. Provisional PatentApplication No. 62/485,457, filed on Apr. 14, 2017, which areincorporated herein by reference.

FIELD OF THE INVENTION

The present application is related generally to polarizing devices.

BACKGROUND

Cube polarizing beam splitters can include a plate-polarizer (array ofwires on a glass substrate) sandwiched between two prisms. See forexample U.S. Pat. Nos. 6,212,014; 7,085,050; and 8,467,128; and USApatent publication numbers US 2007/0297052; US 2007/0297052; US2015/0346497; and US 2017/0068103. The inventions described in thesepatent publications may be sufficient for many traditional applications.

New applications of cube polarizing beam splitters have more demandingspecifications. For example, head-mounted displays may require a verysmall cube polarizing beam splitter, such as for example with a diameterof about 1 mm. A plate-polarizer can be about 0.7 mm thick due tosubstrate thickness, resulting in an overall diameter larger than 1 mmafter being sandwiched between prisms.

Another requirement of some new applications is high heat tolerance.Projection display units are increasingly smaller with higher intensitylight sources, increasing the need for high heat tolerance. The adhesiveused to bond the plate-polarizer to the prisms can fail due to the highheat.

Other optical devices, such as X-Cubes, may also need to be small andhave high heat tolerance.

SUMMARY

It has been recognized that it would be advantageous to providepolarizing optical devices, including cube polarizing beam splitters andX-Cubes, which are small and have high heat tolerance. The presentinvention is directed to various embodiments of polarizing opticaldevices, and methods of making polarizing optical devices, that satisfythese needs. Each embodiment may satisfy one, some, or all of theseneeds.

A method of manufacturing polarizing devices can comprise the followingsteps:

-   1. providing a plate-polarizer including a substrate having a first    side and an opposite, second side, and an array of elongated wires    located at the first side, an imaginary line extending across the    first side and either parallel to or perpendicular to the wires, and    an imaginary plane passing through the imaginary line and    perpendicular to the first side;-   2. cutting a first cut parallel to the imaginary line, at a first    angle that is oblique with respect to the imaginary plane, the first    cut extending through the plate-polarizer from the first side to the    second side;-   3. cutting a second cut parallel to the imaginary line, at a second    angle that is oblique with respect to the imaginary plane, the    second cut extending through the plate-polarizer from the first side    to the second side, the second angle being on an opposite side of    the imaginary plane from the first angle; and-   4. repeating the first cut and the second cut, but shifted over and    spaced to form prisms.

A method of manufacturing a cube polarizer can comprise the followingsteps:

-   1. providing an embedded wire grid polarizer including a first    substrate, a second substrate, and a first array of elongated wires    sandwiched between the first substrate and the second substrate;-   2. cutting a first cut through the embedded wire grid polarizer    parallel to an imaginary line, the imaginary line extending across    an outer-side of the first substrate and either parallel to or    perpendicular to the wires, at a first angle that is oblique with    respect to an imaginary plane, the imaginary plane passing through    the imaginary line and perpendicular to the first array of elongated    wires, the first cut extending through the first substrate, the    second substrate, and the first array of elongated wires;-   3. cutting a second cut through the embedded wire grid polarizer    parallel to the imaginary line, at a second angle that is oblique    with respect to the imaginary plane, the second cut extending    through the first substrate, the second substrate, and the first    array of elongated wires, the second angle being on an opposite side    of the imaginary plane from the first angle; and-   4. repeating the first cut and the second cut, but shifted over and    spaced to form a prism with two pairs of parallel, opposite    cut-sides formed by the first cut and the second cut.

BRIEF DESCRIPTION OF THE DRAWINGS (DRAWINGS MIGHT NOT BE DRAWN TO SCALE)

FIG. 1 is a schematic, perspective-view of a prism 10 with two oppositeends 11 connected to each other by two inner sides 12 and an outer side13, in accordance with an embodiment of the present invention.

FIG. 2 is a schematic end-view of a polarizing cube 20 with four prisms10 combined with the outer sides 13 facing outward, each inner side 12facing an inner side 12 of an adjacent prism 10, mating prism ends 11forming opposite cube ends, and at least one wire grid polarizer 14 atan outer side 13 of at least one of the prisms 10, in accordance with anembodiment of the present invention.

FIGS. 3-6 illustrate steps in methods of manufacturing polarizingdevices, in accordance with embodiments of the present invention.

FIG. 7 shows schematic end-views of prisms 52, which can be made fromthe method illustrated in FIGS. 3-6, in accordance with an embodiment ofthe present invention.

FIGS. 8-10 are schematic end-views of polarizing cubes 80, 90, and 100which can be made by assembling prisms 52 resulting from the methodillustrated in FIGS. 3-6, in accordance with embodiments of the presentinvention.

FIGS. 11-13 illustrate steps in methods of manufacturing cubepolarizers, in accordance with embodiments of the present invention.

DEFINITIONS

As used herein, the term “isosceles trapezoid-shape” means thatnon-parallel sides have equal length and join parallel sides at equalangles. As used in this definition, “equal length” means exactly equallength, equal length within normal manufacturing tolerances, or nearlyequal length, such that any deviation from exactly equal length wouldhave negligible effect for ordinary use of the device.

As used herein, the term “equal” with regard to angles, means exactlyequal, equal within normal manufacturing tolerances, or nearly equal,such that any deviation from exactly equal would have negligible effectfor ordinary use of the device.

As used herein, the term “mm” means millimeter(s).

As used herein, the term “on” means located directly on or located abovewith some other solid material between.

As used herein, the term “parallel” means exactly parallel, orsubstantially parallel, such that planes or vectors associated with thedevices in parallel would intersect with an angle of ≤20°. Intersectionof such planes or vectors can be ≤0.01°, ≤0.1°, ≤1°, ≤5°, ≤10°, or ≤15°if explicitly so stated.

As used herein, the term “perpendicular” means exactly perpendicular, orwithin 20° of exactly perpendicular. The term “perpendicular” can meanwithin 0.1°, within 1°, within 5°, within 10°, or within 15° of exactlyperpendicular if explicitly so stated in the claims.

As used herein, the term “plate-polarizer” means a polarizer with anarray of wires on a sheet or wafer. The sheet or wafer can be flat orplanar with the wires located on one flat or planar side. A width ofthis flat or planar side can be much greater (e.g. at least 10 timesgreater or at least 100 times greater) than a thickness of the sheet orwafer.

As used herein, the term “substrate” means a base material, such as forexample a glass wafer. Unless specified otherwise in the claims, theterm “substrate” also includes any thin film(s) sandwiched between theglass wafer and the wires of the polarizer.

DETAILED DESCRIPTION

As illustrated in FIG. 1, a prism 10 is shown comprising two oppositeends 11 connected to each other by two inner sides 12 and an outer side13. This prism 10, along with additional, similar prisms, can form apolarizing cube.

As illustrated in FIG. 2, four prisms 10 can be combined into apolarizing cube 20 with the outer sides 13 facing outward, each innerside 12 facing an inner side 12 of an adjacent prism 10. Mating prismends 11 can form two opposite cube ends. Examples of shapes of the twoopposite cube ends 11 include square, rectangular, and otherparallelogram shapes.

A first wire grid polarizer 14 a can be located at the outer side 13 ofa first of the four prisms 10 a. A second wire grid polarizer 14 b canbe located at the outer side 13 of a second of the four prisms 10 b. Athird wire grid polarizer 14 c can be located at the outer side 13 of athird of the four prisms 10 c. Although not shown in the figures, theremay be a fourth wire grid polarizer located at the outer side 13 of afourth of the four prisms 10 d. The typical arrangement would be threewire grid polarizers 14 a-c as shown in FIG. 2. Each of the wire gridpolarizers 14 a-c can comprise an array of elongated wires 14. The arrayof elongated wires 14 on one polarizer can be separate from the array ofelongated wires 14 of other wire grid polarizers. The wires 14 of thewire grid polarizers 14 described herein can have small pitch, such asfor example ≤200 nm.

The polarizing cube 20 of FIG. 2 can be a color-combining optic, such asfor example an X-Cube. X-Cubes are sometimes referred to as X-Cubeprisms, X-prisms, light recombination prisms, or cross dichroic prisms.X-Cubes are typically made of four right angle prisms, with dichroiccoatings on one or more of the inner sides 12.

As shown in FIG. 2, the array of elongated wires 14 of each of the wiregrid polarizers 14 a-c can adjoin (can be attached directly to) thematerial (e.g. glass) of the prisms 10 a-c, respectively. This is incontrast to making a plate-polarizer with wires attached to a substrate,then attaching this substrate to the prism. This allows the polarizingcube 20 to be much smaller. For example, the polarizing cube 20 can havea maximum width W₁ of ≤7 mm, ≤4.5 mm, ≤3.4 mm, ≤2.5 mm, ≤2 mm, ≤1.5 mm,≤1.3 mm, ≤1.1 mm, or ≤0.9 mm. The maximum width W₁ can be astraight-line distance, from and perpendicular to one outer side 13, toan opposite outer side 13. This maximum width W₁ can be approximatelytwo times a thickness Th₁ of a substrate 31 of the wire grid polarizer30 (see FIG. 3).

A method of manufacturing polarizing devices, such as for example thepolarizing cubes 20 and 100 of FIGS. 2 and 10 or the polarizing cubes 80and 90 of FIGS. 8-9, can comprise some or all of the following steps.The steps can be performed in the following or other order. There may beadditional steps not described below. These additional steps may bebefore, between, or after those described. This method is illustrated inFIGS. 3-10.

-   1. Providing a plate-polarizer 30 including:    -   a) a substrate 31 having a first side 31 _(a) and an opposite,        second side 31 _(b) (the first side 31 _(a) can be parallel to        the second side 31 _(b)) and a polarizer including an array of        elongated wires 14 located at the first side 31 _(a) (i.e.        located on the first side, embedded in the first side, or        partially embedded in the first side);    -   b) an imaginary line 44 (across the top view in FIG. 4a and into        the page of FIG. 4b ) extending across the first side 31 _(a)        and either parallel to or perpendicular to the wires 14        (parallel to the wires 14 in FIGS. 4a & 4 b);    -   c) an imaginary plane 41 (into the page of FIGS. 4a & 6) passing        through the imaginary line 44 and perpendicular to the first        side 31 _(a).-   2. Cutting a first cut 42 parallel to the imaginary line 44, at a    first angle A₁ that is oblique with respect to the imaginary plane    41, the first cut extending through the plate-polarizer 30 from the    first side 31 _(a) to the second side 31 _(b).-   3. Cutting a second cut 43 parallel to the imaginary line 44, at a    second angle A₂ that is oblique with respect to the imaginary plane    41, the second cut 43 extending through the plate-polarizer 31 from    the first side 31 _(a) to the second side 31 _(b), the second angle    A₂ being on an opposite side of the imaginary plane 41 from the    first angle A₁.-   4. Repeating the first cut 42 and the second cut 43, but shifted    over (distance d1) and spaced to form prisms 52 with ends 11    connected by cut-sides formed by the first cuts 42 and the second    cuts 43 and connected by the first side 31 _(a) and/or the second    side 31 _(b). Each subsequent first cut 42 can have the same oblique    angle as the prior first cut 42, or can be different from the prior    first cut 42. Similarly, each subsequent second cut 43 can have the    same oblique angle as the prior second cut 43, or can be different    from the prior second cut 43.

Prism ends 11 can have various shapes, including a triangle-shape, atrapezoid-shape, or an isosceles trapezoid-shape. The repeated firstcuts 42 and second cuts 43 can form ends 11 with a repeating shape. Eachrepeated imaginary line 44 and imaginary plane 41 can be parallel to thepreceding imaginary line 44 and imaginary plane 41, respectively.

In the above method, the first cut 42 can be made, then the second cut43, then repeated first cut 42/second cut 43. These cuts 42 and 43 canalso be made in another order, such as for example, multiple first cuts42, then multiple second cuts 43.

One way to form repeating ends 11 with a triangle-shape, as shown inFIGS. 4-5, is for the first angle A₁ and the second angle A₂ to be equalto 45° and for the shifted over distance d1 to equal two times athickness Th₁ of the plate-polarizer 30 plus the saw blade kerf. Thefirst angle A₁ and the second angle A₂ can have other values. Forexample, the first angle A₁ and/or the second angle A₂ can be ≥10°,≥30°, or ≥40° and can be ≤50°, ≤60°, or ≤80°.

Repeating ends 11 with a trapezoid-shape are shown in FIG. 6. The firstangle A₁ and the second angle A₂ and/or the shifted over distance d1 canbe adjusted to achieve the desired trapezoid-shape.

Illustrated in FIG. 7 are two prisms 52 resulting from the above method,each prism 52 with ends 11 that are triangle-shaped and connected by twocut sides 72 (formed by the first cuts 42 and the second cuts 43) and anuncut side 71. The uncut side 71 of prism 52 _(w) is the first side 31_(a) with the array of elongated wires 14. The uncut side 71 of prism 52_(x) is the second side 31 _(b) without the array of elongated wires 14.

Illustrated in FIGS. 8-9 are two prisms 52 attached together to formpolarizing cubes 80 and 90 with the uncut-sides 71 facing inward andfacing each other and the cut-sides 72 facing outwards. The uncut-side71 of one of the prisms 52 _(w) of polarizing cube 80 is the first side31 _(a) with the array of elongated wires 14 and the uncut-side 71 ofthe mating prism 52 _(x) is the second side 31 _(a) without the array ofelongated wires 14. The uncut-sides 71 of both prisms 52 _(w) ofpolarizing cube 90 are the first sides 31 _(a) with the arrays ofelongated wires 14. Polarizing cube 80 can have higher transmission ofthe desired polarization and polarizing cube 90 can have highercontrast, so each can be useful for different applications.

Thus, a polarizing cube 80 can include an array of elongated wires 14sandwiched between two prisms 52. Polarizing cube 90 can include twoarrays of elongated wires 14 sandwiched between two prisms 52. Eachprism 52 can include two triangular faces 11 linked by an inner face 71and two outer faces 72.

Polarizing cubes 80 and 90 can have a maximum width W₂ of ≤4 mm, ≤3 mm,≤2.5 mm, ≤2 mm, ≤1.5 mm, ≤1.3 mm, ≤1.1 mm, ≤1.0 mm, or ≤0.6 mm. Themaximum width W₂ can be a straight-line distance, from and perpendicularto one outer face (or uncut-side) 72 to an opposite outer face (oruncut-side) 72 of the other prism.

Illustrated in FIG. 10 are four of the prisms 52 assembled together intoa polarizing cube 100, similar to polarizing cube 20 described above.The ends 11 can be triangle-shaped as shown, or can be another shapesuch as for example isosceles trapezoid-shape or trapezoid-shape. Theuncut-sides 71 can face outward. At least one of the uncut-sides 71 canbe the first side 31 _(a) with the array of elongated wires 14. Two ofthe uncut-sides 71 can be the first side 31 _(a) with the array ofelongated wires 14. As shown in FIG. 10, three of the uncut-sides can befirst sides 31 _(a) with the array of elongated wires 14. Although notshown in the figures, all four of the uncut-sides 71 can be the firstside 31 _(a) with the array of elongated wires 14. Each cut-side 72 canface a cut-side 72 of an adjacent prism 52. The ends 11 can form twoopposite cube ends.

The method described above can result in a very small polarizing cube100. For example, the polarizing cube 100 can have a maximum width W₁ of≤7 mm, ≤4.5 mm, ≤3.4 mm, ≤2.5 mm, ≤2 mm, ≤1.5 mm, ≤1.3 mm, ≤1.1 mm, or≤0.9 mm. The maximum width W₁ can be a straight-line distance, from andperpendicular to one uncut-side 71, to an opposite uncut-side 71.

Another method of manufacturing a cube polarizer can comprise some orall of the following steps. The steps can be performed in the followingor other order. There may be additional steps not described below. Theseadditional steps may be before, between, or after those described.

-   1. Providing an embedded wire grid polarizer 110 or 120 (e.g.    plate-polarizer):    -   a. As shown in FIG. 11, embedded wire grid polarizer 110        includes a first substrate 31 f, a second substrate 31 s, and a        first array of elongated wires 14 f sandwiched between the first        substrate 31 f and the second substrate 31 s. The first array of        elongated wires 14 f can be attached to, and can adjoin, the        first substrate 31 f and the second substrate 31 s. The first        array of elongated wires 14 f can be on, in, or partially in the        first substrate 31 f and/or the second substrate 31 s. Starting        with embedded wire grid polarizer 110 can result in polarizing        cube 80, as shown in FIG. 8.    -   b. As shown in FIG. 12, embedded wire grid polarizer 120        includes the first array of elongated wires 14 f, plus a second        array of elongated wires 14 s, both sandwiched between the first        substrate 3 f and the second substrate 31 s. The first array of        elongated wires 14 f can be attached to, can adjoin, and can be        on, in, or partially in the first substrate 31 f. The second        array of elongated wires 14 f can be attached to and can adjoin        the first array of elongated wires 14 f and to the second        substrate 31 s. The second array of elongated wires 14 f can        adjoin and be on, in, or partially in the second substrate 31 s.        Starting with embedded wire grid polarizer 120 can result in        polarizing cube 90, as shown in FIG. 9.-   2. Cutting a first cut 42 through the embedded wire grid polarizer    110 parallel to an imaginary line 44, the imaginary line 44    extending across an outer-side of the first substrate 31 f and    either parallel to or perpendicular to the wires (the imaginary line    44 extending into the page of FIG. 13), at a first angle A₁ that is    oblique with respect to an imaginary plane 41, the imaginary plane    41 passing through the imaginary line 44 and perpendicular to the    first array of elongated wires 14 f, the first cut 42 extending    through the first substrate 31 f, the second substrate 31 s, and the    first array of elongated wires 14. See FIG. 13.-   3. Cutting a second cut 43 through the embedded wire grid polarizer    parallel to the imaginary line 44, at a second angle A₂ that is    oblique with respect to the imaginary plane 41, the second cut 43    extending through the first substrate 31 f, the second substrate 31    s, and the first array of elongated wires 14, the second angle A₂    being on an opposite side of the imaginary plane 41 from the first    angle A₁. See FIG. 13.-   4. Repeating the first cut 42 and the second cut 43, but shifted    over (distance d2) and spaced to form a prism with two pairs of    parallel, opposite cut-sides formed by the first cut 42 and the    second cut 43. Each repeated imaginary line 44 and imaginary plane    41 can be parallel to the preceding imaginary line 44 and imaginary    plane 41, respectively. See FIG. 13.

In the above method, the first cut 42 can be made, then the second cut43, then repeated first cut 42/second cut 43. These cuts 42 and 43 canalso be made in another order, such as for example, multiple first cuts42, then multiple second cuts 43.

A result of this method can be polarizing cubes similar to thepolarizing cubes 80 or 90 in FIGS. 8-9, which can have characteristicsof the polarizing cubes 80 or 90 as described herein. To form polarizingcubes with square-shaped ends, similar to polarizing cubes 80 or 90, thefirst angle A₁ and the second angle A₂ can each equal 45°, and theshifted over distance d2 can equal a thickness Th₂ of the embedded wiregrid polarizer 120 or 130, respectively, plus the saw blade kerf. Thefirst angle A₁, the second angle A₂, and the shifted over distance d2can be adjusted for other parallelogram-shapes. In one embodiment, thefirst angle A₁ and the second angle A₂ can have the same magnitude.

In the various embodiments described herein, the arrays of elongatedwires 14, 14 f, and 14 s can be on the outer side 13, the first side 31a, the first substrate 31 f, or the second substrate 31 s (e.g. see U.S.Pat. No. 6,208,463). The arrays of elongated wires 14, 14 f, and 14 scan be in or partially in the outer side 13, the first side 31 a, thefirst substrate 31 f, or the second substrate 31 s. USA patentpublication number US 2014/0300964 teaches wires in the substrate.Alternatively, wires can be patterned on a substrate, then an overcoat,applied by methods such as for example spin-on glass or atomic layerdeposition, can embed the wires.

An advantage of embedding the array of elongated wires 14 isfacilitating an adhesive-free bonding technique to bond the two prismstogether. Use of an adhesive-free bonding technique can allow theoptical device to withstand higher temperatures. If an adhesive is usedinstead of an adhesive-free bonding technique, then the adhesive mightfail at high temperatures. Use of an adhesive-free bonding technique canallow use at high temperatures. Thus, at least for some applications, anadhesive-free bonding technique may be preferred.

Attachment methods described herein, including the inner sides 12 of thepolarizing cube 20, the prisms 52 attached together to form polarizingcubes 80 and 90, the first array of elongated wires 14 f attached to thesecond substrate 31 s in embedded wire grid polarizer 110, and the firstarray of elongated wires 14 f attached to the second array of elongatedwires 14 s in embedded wire grid polarizer 120, can be done with anadhesive or by an adhesive-free bonding technique.

What is claimed is:
 1. A method of manufacturing a cube polarizer, themethod comprising: providing an embedded wire grid polarizer including afirst substrate, a second substrate, and a first array of elongatedwires sandwiched between the first substrate and the second substrate;cutting a first cut through the embedded wire grid polarizer parallel toan imaginary line, the imaginary line extending across an outer-side ofthe first substrate and either parallel to or perpendicular to thewires, at a first angle that is oblique with respect to an imaginaryplane, the imaginary plane passing through the imaginary line andperpendicular to the first array of elongated wires, the first cutextending through the first substrate, the second substrate, and thefirst array of elongated wires; cutting a second cut through theembedded wire grid polarizer parallel to the imaginary line, at a secondangle that is oblique with respect to the imaginary plane, the secondcut extending through the first substrate, the second substrate, and thefirst array of elongated wires, the second angle being on an oppositeside of the imaginary plane from the first angle, and the first angleequals the second angle; and repeating the first cut and the second cut,but shifted over and spaced to form polarizing cubes, each cubeincluding a pair of prisms, each cube has two pairs of opposite,parallel cut-sides formed by the first cut and by the second cut, thecut-sides facing outwards, each end of each prism has a triangle-shapeor an isosceles trapezoid-shape.
 2. The method of claim 1, whereinrepeating the first cut and the second cut includes multiple first cutsthen multiple second cuts.
 3. The method of claim 1, further comprisinga second array of elongated wires, attached to and sandwiched betweenthe second substrate and the first array of elongated wires.
 4. A methodof manufacturing a cube polarizer, the method comprising: providing anembedded wire grid polarizer including a first substrate, a secondsubstrate, and a first array of elongated wires sandwiched between thefirst substrate and the second substrate; cutting a first cut throughthe embedded wire grid polarizer parallel to an imaginary line, theimaginary line extending across an outer-side of the first substrate andeither parallel to or perpendicular to the wires, at a first angle thatis oblique with respect to an imaginary plane, the imaginary planepassing through the imaginary line and perpendicular to the first arrayof elongated wires, the first cut extending through the first substrate,the second substrate, and the first array of elongated wires; cutting asecond cut through the embedded wire grid polarizer parallel to theimaginary line, at a second angle that is oblique with respect to theimaginary plane, the second cut extending through the first substrate,the second substrate, and the first array of elongated wires, the secondangle being on an opposite side of the imaginary plane from the firstangle; and repeating the first cut and the second cut, but shifted overand spaced to form polarizing cubes, each cube including a pair ofprisms, each cube has two pairs of opposite cut-sides formed by thefirst cut and by the second cut, the cut-sides facing outwards.
 5. Themethod of claim 4, wherein each end of each prism has a triangle-shape.6. The method of claim 4, wherein each end of each prism has anisosceles trapezoid-shape.
 7. The method of claim 4, wherein the twoopposite cut-sides of each pair are parallel with respect to each other.8. The method of claim 4, wherein repeating the first cut and the secondcut includes multiple first cuts then multiple second cuts.
 9. Themethod of claim 4, wherein repeating the first cut and the second cutincludes making the first cut, then making the second cut, thenrepeating in this order.
 10. The method of claim 4, wherein theimaginary line is parallel to the wires.
 11. The method of claim 4,further comprising a second array of elongated wires, attached to andsandwiched between the second substrate and the first array of elongatedwires.
 12. The method of claim 4, wherein the first array of elongatedwires are embedded in the first substrate and the second substrate isbonded to the first array of elongated wires by an adhesive-free bondingtechnique.
 13. The method of claim 4, wherein a maximum width is ≤2 mm,the maximum width being a straight-line distance, from a cut-side to anopposite cut-side.
 14. The method of claim 4, wherein the first angleequals 45° and the second angle equals 45°.
 15. A method ofmanufacturing a cube polarizer, the method comprising: providing anembedded wire grid polarizer including a first substrate, a secondsubstrate, and a first array of elongated wires sandwiched between thefirst substrate and the second substrate; cutting a first cut throughthe embedded wire grid polarizer parallel to an imaginary line, theimaginary line extending across an outer-side of the first substrate andeither parallel to or perpendicular to the wires, at a first angle thatis oblique with respect to an imaginary plane, the imaginary planepassing through the imaginary line and perpendicular to the first arrayof elongated wires, the first cut extending through the first substrate,the second substrate, and the first array of elongated wires; cutting asecond cut through the embedded wire grid polarizer parallel to theimaginary line, at a second angle that is oblique with respect to theimaginary plane, the second cut extending through the first substrate,the second substrate, and the first array of elongated wires, the secondangle being on an opposite side of the imaginary plane from the firstangle; and repeating the first cut and the second cut, but shifted overand spaced to form a prism with two pairs of parallel, oppositecut-sides formed by the first cut and the second cut.
 16. The method ofclaim 15, further comprising a second array of elongated wires, attachedto and sandwiched between the second substrate and the first array ofelongated wires.
 17. The method of claim 15, wherein the first array ofelongated wires are embedded in the first substrate and the secondsubstrate is bonded to the first array of elongated wires by anadhesive-free bonding technique.
 18. The method of claim 15, wherein amaximum width is ≤2 mm, the maximum width being a straight-linedistance, from a cut-side to an opposite cut-side.
 19. The method ofclaim 15, wherein the first angle equals 45° and the second angle equals45°.
 20. The method of claim 15, wherein the imaginary line is parallelto the wires.